The non-exclusive agreement covers an approximately three-year term. Ironwood will collaborate with Alnylam on AHP disease education designed to help ensure AHP patients are accurately diagnosed and to support access to treatment with givosiran once prescribed (assuming approval).

Ironwood will receive fixed payments and royalties in the mid-teens % on net sales generated from prescriptions or referrals from certain physicians related to Ironwood's promotional efforts.

Alnylam will maintain responsibility for all other aspects of givosiran, and retains all global development and commercialisation rights.

Acute hepatic porphyria refers to a family of rare, genetic diseases characterized by potentially life-threatening attacks and for some patients chronic debilitating symptoms that negatively impact daily functioning and quality of life.

AHP is comprised of four subtypes, each resulting from a genetic defect leading to deficiency in one of the enzymes of the heme biosynthesis pathway in the liver: acute intermittent porphyria, hereditary coproporphyria, variegate porphyria, and ALAD-deficiency porphyria.

These defects cause the accumulation of neurotoxic heme intermediates aminolevulinic acid and porphobilinogen, with ALA believed to be the primary neurotoxic intermediate responsible for causing both attacks and ongoing symptoms between attacks.

Common symptoms of AHP include severe, diffuse abdominal pain, weakness, nausea, and fatigue.

The nonspecific nature of AHP signs and symptoms can often lead to misdiagnoses of other more common conditions such as irritable bowel syndrome, appendicitis, fibromyalgia, and endometriosis, and consequently, patients afflicted by AHP often remain without a proper diagnosis for up to 15 years.

In addition, long-term complications of AHP and its treatment can include chronic neuropathic pain, hypertension, chronic kidney disease and liver disease, including iron overload, fibrosis, cirrhosis and hepatocellular carcinoma.

Currently, there are no treatments approved to prevent debilitating attacks or to treat the chronic manifestations of the disease.

Givosiran is an investigational, subcutaneously administered RNAi therapeutic targeting aminolevulinic acid synthase 1 (ALAS1) in development for the treatment of acute hepatic porphyria.

By reducing accumulation of these intermediates, givosiran has the potential to prevent or reduce the occurrence of severe and life-threatening attacks, control chronic symptoms, and decrease the burden of the disease.